Valve actuating means

ABSTRACT

Hydraulic actuating means for the spring-returned admission valve of a reciprocating expansion motor comprises a plunger pump delivering oil under pressure to a slave cylinder the piston of which is connected to said admission valve, an automatic nonreturn filling valve for said pump and controllable means for spilling oil displaced by the pump at any desired point in the delivery stroke of the pump plunger thereby determining the period of opening of said admission valve.

United States Patent n51 3,683,874 Berlyn [4 Aug. 15, 1972 A [54] VALVEACTUATING MEANS 2,602,434 7/1952 Barnaby ..l23/90.l2 I [721 Invent 9 ifiz 't gg gi FOREIGN PATENTS OR APPLICATIONS I I gland 1,172,416 10/1958France ..l23/90.l2 [221 Filed= Sept 8, 1970 Primary Examiner-Al LawrenceSmith 21 APP] 70 075 Attorney--Norris and Bateman [57] ABSTRACT [52] US.Cl ..IZ 3/90.l2, l23/90.l6 [51] Int. Cl ..FOII 9/02 Y F actuating meansf" the spnflg'retumed Search. 1 1 2 l 3 mlSSlOn valve ofa reclprocatmgexpanslon mOtOl coma prises a plunger pump delivering; oil underpressure to [56] References Cited a slave cylinder the piston of whichis connected to said admission valve, an automatic non-return fillingUNITED STATES PATENTS vallve forl peudmtp agld controllabled means forspi ing oi isp ac y t e pump at any esired point 53: 2 In the dellverystrolte of the pump plunger thereby 1864 8/1935 z' dzltemunmg the periodof opening of said admIssIon- 1,876,735 9/1932 Noble ..l23/90.l22,002,196 5/1935 Ucko ..123/90. 12 X 6 Claim, 2 Drawing Figures 4 l l- I20 w v 1 I I 2% I i 29 .87 I l 37 T L3 u 1' ,a/jlml I {38 41/42 7 3g 1 FA 40 T 7- 3O 31 PATENTEDAUG 15 I972 3.683. 874 sum 1 or 2 FIG. 7.

INVESTOR MARTIN JOHN B! NORRTS 8| BATEI'HN PATENTEDMI: 15 m2 SHEET 2 0F2 FIG. 2.

57 5a 56 s0 s1. 52

N (A) m INVENTOR MARTIN JOHN BLRLYN 74% w flaw NORRIS & BATmq q Thisinvention relates to actuating means for the spring-returned admissionvalve of a reciprocating expansion motor of the type in which modulationof power output is effected by varying the period of time in each cycleof operation during which the admission valve is held open.

In the operation of reciprocating expansion motors it is known that themost efficient method of modulating the power output is to open theadmission valve at a constant angle of the expansion motor crank and tovary or modify the crank angle at which the said valve closes, butheretofore no efficient mechanism has been devised for achieving thisdesired mode of control.

More particularly the invention provides an improved hydraulic valveactuating mechanism for use in these circumstances and which effectsopening of the admission valve at a substantially constant angle of theexpansion motor crank, whilst being controlled to close the valve at anycrank angle up to about 120 from the angle at valve opening.

Another feature of the improved valve actuating mechanism is thatthrough the greater part of the controlled range of crank angles atwhich valve closing can be caused to occur valve travel from closedposition is substantially constant, whilst a further feature of thismechanism is that regardless of crankshaft speed a rapid valve closureis obtained over the normal range of valve open duration.

In the valve actuating means according to the invention a plunger pump,adapted to deliver oil under high pressure to a slave cylinder fittedwith a piston having operable connection with the spring-returnedadmission valve, is provided with an automatic non-return filling valveand controllable spill means whereby oil displaced by the plunger may bespilled at any desired point in the delivery stroke of the plunger to azone of relatively low pressure thereby determining the length of theperiod during which the admission valve is held open.

In the preferred embodiment the slave piston abuts a positive stop whenat that end of its stroke corresponding to the closed position of theadmission valve,the slave cylinder being provided with a spill port inits wall communicating with a sump and said spill port being so locatedas to be uncovered by the slave piston when the latter has moved fromthe positive stop by an amount corresponding to the travel of saidadmission valve from closed to full open" position.

Reference will now be made to the accompanying drawings which illustratea preferred embodiment of the invention and wherein:

FIG. 1 is a sectional view of an expansion motor embodying the improvedvalve actuating means, and

FIG. 2 is an enlarged sectional view of said valve actuating means.

As shown in FIG. 1, the expansion motor comprises basically crankcasefitted with sump l 1 and supporting cylinder 12 which is closed bycylinder head 13.'

Piston 14 in cylinder 12 drives crank 15 through connecting rod 16,cylinder 12 being provided with a ring of exhaust ports 17 opening intoexhaust manifold 18 having outlet 19. Cylinder head 13 is fitted withadmission valve 20 for controlling flow of hot vapour under pressurefrom inlet 21 to admission port 22, admission valve 20 being urgedtowards its closed position by spring 23 and being opened by the valveactuator indicated generally at 26 and which will now be described withreference to FIG. 2.

The valve actuator includes pump plunger 27 having a fluid-sealingsliding fit in two co-axial bores 28 and 29 in actuator housing 30,plunger 27 being driven on its pressure stroke by earn on camshaft 24which is journalled in crankcase 10 (FIG. 1) and driven from crank 15(FIG. 1), plunger 27 being returned on its suction stroke by spring 31.Plunger 27 is provided with peripheral groove 32, axial duct 33 andradial duct 34 which completes a fluid path from axial duct 33 toperipheral groove 32. Control sleeve 35 is a fluid-sealing sliding fiton pump plunger 27 and is provided with flanges 36 for engagingeccentric pin 37 formed on one end of control shaft 38 which may berocked about its axis by control lever 39 fixed to the end of controlshaft 38 remote from eccentric pin 37. Control shaft 38 is journalled incover plate 40 of housing and inlet duct 41 in boss 42 of housing 30conveys oil at a relatively low pressure, conveniently from the oil inthe lubricating system of the expansion motor, into space 43 in housing30. Annular valve 44 is urged towards concentric outer and inner lands45 and 46 respectively by spring 47 and between lands 45 and 46 isannular groove 48 into which oil from space 43 can flow by way of ducts49.

On the upper end of housing 30 is slave cylinder 50 connected byduct 51and bore 52 to pump chamber 53 in which is located spring-loaded valve44, said bore 52 being provided with annular groove 54 loading to duct55 which conveys oil from said annular groove to a point from which itfalls into sump 11 (FIG. 1). Slave piston 56 is a fluid-sealing slidingfit in bore 52 and is flanged at 57 to abut face 58 on slave cylinder 50when slave piston 56 is fully retracted into bore 52.

The operation of the valve actuator is as follows: Plunger 27 movingupwards applies pressure to oil in pump chamber 53 and this pressureacting on slave piston 56 by way of duct 51 and bore 52 causes slavepiston 56 to move valve 20 to the full open position shown in FIG. 1.Slave piston 56 having now uncovered the edge of annular groove 54,further upward movement of plunger 27 does not result in continuedmovement of valve 20 in the opening direction but causes oil to berejected from bore 52 by way of annular groove 54 and duct 55 to sump 11(FIG. 1). As plunger 27 continues to move upwards due to continuedcounterclockwise rotation of cam 25, peripheral groove 32 emerges fromcontrol sleeve 35. However, the oil pressure acting on slave piston 56is sufficient to balance the force due to spring 23 and is much higherthan the relatively low oil pressure in space 43. Thus the uncovering ofperipheral groove 32 by control sleeve 35 results in slave piston 56being forced back in bore 52 by spring 23, driving oil down axial duct33 and, by way of radial duct 34 and peripheral groove 32, into space43. Thus valve 20 (FIG. 1) is returned rapidly to closed position byspring 23 even though cam 25 is still moving plunger 27 in thevalveppening direction, there being now insuflicient oil pressure actingon the slave piston to resist the valve closing action of spring 23.

It will be apparent that angular displacement of control level 39 willchange the location of control sleeve 25 along the axis of plunger 27and, if control sleeve 35 is raised to a higher location than that shownin FIG. 2, cam 25 will have to rotate further in a counterclockwisedirection before peripheral groove 32 emerges from control sleeve 35 andallows valve 20 (FIG. 1) to close. Conversely, lowering control sleeve35 causes valve 20 (FIG. 1) to close at an earlier point in the rotationof cam 25 than that shown. When the crest of cam 25 has passed throughthe centre line of plunger 27 the latter begins to descend. When flange57 abuts face 28 further downward movement of plunger 27 causes apressure drop in pump chamber 53 and this pressure drop over annularvalve 44, and the pressure of oil in space 43, combine to create anupward force on valve 44 which, overcoming the downward force of spring47, lifts valve 44 off concentric lands 45 and 46 so that oil flows fromspace 43 into pump chamber 53 by way of ducts 49 and annular groove 48.

When cam 25 has rotated so far that plunger 27 is in contact with thebase circle of cam 25, plunger 27 remains static in its lowest positionfor approximately a half a revolution of the camshaft and this givesspring 47 time to accelerate valve 44 back into seating contact withlands 45 and 46 ready for the next cycle of valve actuation.

The volumetric displacement of plunger 27 over its full stroke issubstantially in excess of, and preferably about two-and-a-half times,the volumetric displacement of slave piston 56 over its travel betweenabutment of flange 57 against face 58 of slave cylinder 50 and theuncovering of annular groove 54 of slave cylinder 50 by slave piston 56.

With control sleeve 35 in its highest position peripheral groove 32 doesnot emerge fron control sleeve 35 in any position of cam 25 and valve 20(FIG. 1) does not begin to move towards closed position until the crestof cam 25 has passed through the centre line of plunger 27. Thiscondition provides maximum duration of valve opening and would normallyonly be used for starting the expansion motor from standstill.

It will be noted that vertical adjustment of the position of controlsleeve 35 affects only the closing point, that is the duration ofopening, of valve 20 (FIG. 1). Regardless of the position of controlsleeve 35 slave piston 56 will not move beyond the point at which spillinto annular groove 54 takes place and therefore the distance by whichvalve 20 (FIG. 1) is lifted from closed position is dissociated from theduration of its opening. a

If it is a requirement that the expanion motor should be reversible,means may be provided for re-phasing camshaft 24 in relation to crank(FIG. 1).

I claim:

1. Hydraulic actuating means for a spring-returned admission valve of areciprocating expansion motor comprising a slave cylinder, a slavepiston in said cylinder operatively connected to said admission valve, aspill port in said slave cylinder uncovered by said slave piston at apoint in its travel corresponding to the fully open position of saidadmission valve to thereby determine the stroke of said slave piston,pump means including a reciprocable plunger and a pump chamber connectedto said slave cylinder, rotary cam means operable to initiatedisplacement of said plunger at a constant angular position of said cammeans to deliver oil under pressure from said pump chamber to said slavecylinder, oil supply means, means connecting said oil supply means tosaid pump chamber and including an automatic non-retum filling valve forsaid pump chamber, said filling valve including an annular plate valvemember spring-biased towards a closed position and movable to anopen-position during the suction stroke of said plunger to deliver oilfrom said supply means to said pump chamber, and controllable spillmeans for spilling oil from said pump chamber, said spill meansincluding adjustable means movable axially along said pump plunger andoperable to spill oil from said pump chamber at any desired point in thedelivery stroke of said plunger to thereby determine the duration ofopening of said admission valve.

2. Hydraulic actuating means as defined in claim 1, wherein saidcontrollable spill means comprises a transverse duct formed in said pumpplunger and a passageway extending between said transverse duct and thedelivery end of said plunger, and said adjustable means comprises anormally stationary control sleeve adjustable axially along said plungerand operable to uncover said transverse duct at a desired point in thedelivery stroke of said plunger.

3. Hydraulic actuating means as claimed in claim 2 including a controlshaft having eccentric means engageable with said control sleeve andmeans to turn said shaft and thereby displace said sleeve axially ofsaid plunger.

4. Hydraulic actuating means as defined in claim 2, wherein said oilsupply means comprises a low pressure oil chamber separated from saidpump chamber by said annular plate valve member.

5. Hydraulic actuating means as defined in claim 4, wherein said annularplate valve member surrounds the delivery end of said pump plunger andcontrols the flow of oil through a passageway connecting said lowpressure chamber to said pump chamber.

6. A reciprocating expansion motor comprising a crankcase, a cylindermounted on said crankcase, a piston reciprocable in said cylinder, acrank drive connected to said piston, a spring returned admission valvefor controlling the flow of fluid to said cylinder, hydraulic actuatingmeans for said admission valve including a slave cylinder, a slavepiston in said cylinder operatively connected to said admission valve, aspill port in said slave cylinder connected to said crankcase anduncovered by said slave piston at a point in its travel corresponding tothe fully open position of said admission valve to thereby determine thestroke of said slave piston, pump means including a reciprocable plungerand a pump chamber connected to said slave cylinder, rotary cam meansdriven from said crank and operable to initiate displacement of saidplunger at a constant angular position of said cam means to deliver oilunder pressure from said pump chamber to said slave cylinder, oil supplymeans connected to said crankcase, means connecting said oil supplymeans to said pump chamber and including an automatic nonretum fillingvalve for said pump chamber, said filling valve including an annularplate valve member springbiased towards a closed position during thedelivery stroke of said plunger and movable to an open position duringthe return stroke of said plunger to deliver oil from said supply meansto said pump chamber, and controllable spill means for spilling oil fromsaid pump chamber back to said oil supply means, said spill meansincluding adjustable means movable axially along said pump plunger andoperable to spill oil from said pump 5 chamber at any desired point inthe delivery stroke of said plunger to thereby determine the duration ofopening of said admission valve.

1. Hydraulic actuating means for a spring-returned admission valve of areciprocating expansion motor comprising a slave cylinder, a slavepiston in said cylinder operatively connected to said admission valve, aspill port in said slave cylinder uncovered by said slave piston at apoint in its travel corresponding to the fully open position of saidadmission valve to thereby determine the stroke of said slave piston,pump means including a reciprocable plunger and a pump chamber connectedto said slave cylinder, rotary cam means operable to initiatedisplacement of said plunger at a constant angular position of said cammeans to deliver oil under pressure from said pump chamber to said slavecylinder, oil supply means, means connecting said oil supply means tosaid pump chamber and including an automatic non-return filling valvefor said pump chamber, said filling valve including an annular platevalve member spring-biased towards a closed position and movable to anopen position during the suction stroke of said plunger to deliver oilfrom said supply means to said pump chamber, and controllable spillmeans for spilling oil from said pump chamber, said spill meansincluding adjustable means movable axially along said pump plunger andoperable to spill oil from said pump chamber at any desired point in thedelivery stroke of said plunger to thereby determine the duration ofopening of said admission valve.
 2. Hydraulic actuating means as definedin claim 1, wherein said controllable spill means comprises a transverseduct foRmed in said pump plunger and a passageway extending between saidtransverse duct and the delivery end of said plunger, and saidadjustable means comprises a normally stationary control sleeveadjustable axially along said plunger and operable to uncover saidtransverse duct at a desired point in the delivery stroke of saidplunger.
 3. Hydraulic actuating means as claimed in claim 2 including acontrol shaft having eccentric means engageable with said control sleeveand means to turn said shaft and thereby displace said sleeve axially ofsaid plunger.
 4. Hydraulic actuating means as defined in claim 2,wherein said oil supply means comprises a low pressure oil chamberseparated from said pump chamber by said annular plate valve member. 5.Hydraulic actuating means as defined in claim 4, wherein said annularplate valve member surrounds the delivery end of said pump plunger andcontrols the flow of oil through a passageway connecting said lowpressure chamber to said pump chamber.
 6. A reciprocating expansionmotor comprising a crankcase, a cylinder mounted on said crankcase, apiston reciprocable in said cylinder, a crank drive connected to saidpiston, a spring returned admission valve for controlling the flow offluid to said cylinder, hydraulic actuating means for said admissionvalve including a slave cylinder, a slave piston in said cylinderoperatively connected to said admission valve, a spill port in saidslave cylinder connected to said crankcase and uncovered by said slavepiston at a point in its travel corresponding to the fully open positionof said admission valve to thereby determine the stroke of said slavepiston, pump means including a reciprocable plunger and a pump chamberconnected to said slave cylinder, rotary cam means driven from saidcrank and operable to initiate displacement of said plunger at aconstant angular position of said cam means to deliver oil underpressure from said pump chamber to said slave cylinder, oil supply meansconnected to said crankcase, means connecting said oil supply means tosaid pump chamber and including an automatic non-return filling valvefor said pump chamber, said filling valve including an annular platevalve member spring-biased towards a closed position during the deliverystroke of said plunger and movable to an open position during the returnstroke of said plunger to deliver oil from said supply means to saidpump chamber, and controllable spill means for spilling oil from saidpump chamber back to said oil supply means, said spill means includingadjustable means movable axially along said pump plunger and operable tospill oil from said pump chamber at any desired point in the deliverystroke of said plunger to thereby determine the duration of opening ofsaid admission valve.